The week in pictures: 20 December 2013

Whirling dervishes perform at the Galata Mevlevihane (The Lodge of the Dervishes) in Istanbul, Turkey. The dervishes are adepts of Sufism, a mystical form of Islam that preaches tolerance and a search for understanding. Those who whirl, like planets around the sun, turn dance into a form of prayer.Picture: GURCAN OZTURK/AFP/Getty Images